Adventure of the Creeping Man

Jack Bennett asks Sherlock to investigate his employer and future father-in-law Professor Presbury. The professor's personality and behavior have suddenly changed. Bennett fears that Professor Presbury could become dangerous. As does the professor's daughter Edith. The changes in the professor's character have coincided with his dog taking a sudden violent dislike towards him. While Bennett is discussing the case with Holmes, Edith arrives. She says she saw her father's face at her bedroom window the previous night. The problem is her bedroom is on the second floor and there is no way for any man to have been able to get to that window.

Presbury is a widower engaged to a considerably younger woman, Alice Morphy. The Professor is quite displeased at hearing that Bennett, who also happens to be his assistant, has hired the Great Detective. He escorts Holmes and Watson off the property. When Holmes reads of thefts from zoos — all monkeys and apes — he begins to unravel the mystery.

This is definitely one of the more extraordinary and fantastical stories of the Holmes canon. With a extremely odd climax which verges on science fiction.